Hi all,
I wonder if anyone out there can help me identify a problem which only cropped up last Sunday, 400 miles into running in my newly refurbished ES2 motor.
I was riding down from Catania to Pozzallo (Sicily) to catch the ferry that crosses over to Malta. It was pretty hot and I was travelling at a constant 50mph. Suddenly the engine started popping and banging. I throttled down and the banging stopped, so I carried on as though nothing had happened. 10 miles further down the same road it happened again, but this time the motor cut out. I coasted to the side of the road put the bike up on its centerstand, kicked the starter and I was off again. Got to the ferry without further mishap.
I cannot make up my mind if this popping and banging was due to;
a) Fuel vaporization due to excessive heat. (stubb mounted carb on the ES2 no heat shield).
b) A sticking exhaust valve due to over oiling.
c) Break down of the magneto condenser at high speed.
I tend to favour reason (c) as I did find some white deposit on the mag points but could not see any excessive arcing of the points when running. I only saw some sparks when I raced the engine.
I am a little lost so any help would be very much appreciated.
Albert Pisani
Malta
Other possible causes: Wro…
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As mike said, it will be a…
As mike said, it will be a process of elimination.
Magnetos work better at higher revs so I doubt it is breaking down due the the speed. However the insulation on the coil and elsewhere in the mag will deteriorate as it gets hotter so it could be related to the heat. The normal sign of a dodgy mag is when you can't start the bike once it is warm (typical example is you stop for fuel and can't start it after). Once the bike is running its normally ok, unless it has got really bad, but that doesn't happen overnight and you would probably have seen other symptoms first. Some arching at high revs is also normal, you will see that on most mags.
Given the situation you described, I would start by looking and carburation and work through from there.
Good luck!
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Hi Mike & Andy, Many t…
Hi Mike & Andy,
Many thanks for your suggestions. Yes I realise that it will have to be a process of elimination and that is why I am trying to narrow down the field. What I find odd is that up to that point the bike worked faultlessly as it also did after the fault manifested itself the second time. I feel that the sustained speed must have something to do with it. And in that case would direct me to the fuel system.
What pointed me to the mag capacitor really was the fluffy white deposits on the points and the high speed arching, can I consider this as being normal? But on the other hand the bike did start first kick after it cut out.
I will start with the fuel system first, checking for a sticking float, dirt and blocked jets. There is a very remote chance that my tank bag may have blocked or restricted the vent hole on my tank cap. So I will check that too. Then I suppose it will have to be a blast down the by-pass in the hope that something happens as I hit 50 and keep it there for as long as I can.
Many thanks,
Albert
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Hi Albert, first, I must a…
Hi Albert, first, I must admit that I have never owned a Norton single. However, I have owned other makes. I appreciate that you are still running in your rebuilt engine, but, a cruising speed of 50 m.p.h. seems a bit slow. Possibly the auto advance is not "kicking in", and your ignition is too retarded. The actual speed, whilst running in, is not so important as keeping a light load on the motor. In fact, to run in at a constant speed has never been recommended. I hope you get it sorted quickly, summer does not last too long (except here in Spain!). John..
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Other possible causes:
Wrong jetting/needle position (what does the plug look like?)
Wrong float height setting
Valve settings too tight
Ignition timing off
Petcock clogged and not letting enough fuel through at speed
Good luck, I think that it will be a process of elimination.
Mike